Photographic emulsions sensitized with cyanine dyestuffs



United States Patent 9 Claims. cl. 96-105) This application is a continuation-in-part of application Serial No. 324,037, filed November 15, 1963.

The invention relates to novel polymethine dyestuffs of the rhodacyanine type and to silver halide emulsions, more especially emulsions containing color couplers, which are sensitized with these dyestuffs.

These dyestuffs have become important as sensitizers for photographic silver halide emulsions since they are particularly stable with respect to other additives, particularly to color couplers. They are described, for example, German Patents Nos. 890,249 and 921,668 or in British Patent No. 489,335. The class was later enlarged by the introduction into the methine chain of substituents which bring about distinct bathochromic shifts. The sensitization curves of all these dyestuffs have, however, the disadvantage of being highly unsymmetrical: apart from the main maximum, there is a secondary maximum at shorter Wavelength. This secondary sensitization is undesirable in color photography, since it impairs sharp separation of the sensitivities. This obviously applies not only to the multi-layer processes, but also to mixed-grain emulsions or screen processes, since selective sensitization is alway necessary for the individual regions of the spectrum. As an improvement, it has been proposed to use additional color filter layers which are intended to exclude this secondary sensitivity. Apart from the difficulty of finding filter dyestuffs which are satisfactry photographically and show the necessary intensity and correct position of the absorption, an additional layer also requires a considerable additional technical expenditure.

The present invention has for its object to modify the rhodacyanines in such a way that the secondary maximum disappears and the sensitization curve is, as far as possible, symmetrical, but the modified rhodacyanines are still capable of sufficient variation in order that the sensitization maximum can be adapted to the actual use, i.e., to the absorption maximum of a dyestuff image to be recorded.

It has now been found that these conditions are satisfied by dyestuffs of the following formula:

Wherein R represents hydrogen atoms, alkyl groups, preferably with not more than carbon atoms, which can be substituted by carboxyl, sulphonic acid, sulphonamide or hydroxyl groups, unsaturated alkyl groups with 2 to 5 carbon atoms, such as allyl or an aralkyl group such as benzyl, which can be substituted by a sulfonic acid p;

R represents hydrogen atoms, alkyl, advantageously having 1 to 5 carbon atoms, aralkyl or aryl radicals, such as benzyl or phenyl;

n represents 0, 1 or 2;

m represents 1, 2 or 3;

3,357,833 Patented Dec. 12, 1967 X represents any anion which is usual in cyanine chemistry, such as chloride, bromide, iodide, perchlorate, thiocyanate, benzenesulfonate, p-toluene sulfonate, methylsulfate, ethylsulfate;

Y represents atoms or radicals necessary to complete a heterocyclic ring, which is usual in cyanine chemistry and such rings are advantageously oxazole, benzoxazole, thiazole, benzthiazole, thiodiazole, pyrimidine, pyroline, benzimidazole, tetrazole, azacycloheptamethylene, selenazole or benzselenazole, naphthoxazole, oxadiazole, pyridine, pyridiazine, quinoline, triazine, thiazine, triazole, triazoline, pyrazoline or indoline;

Z represents S, 0, Se or NR whereby R represents hydrogen or an alkyl radical, preferably having 1 to 5 carbon atoms.

The heterocyclic radicals can in their turn be substituted, for example, by alkyl groups, with advantageously up to 6 carbon atoms, cycloalkyl, such as cyclohexyl, aralkyl, such as benzyl, aryl, such as phenyl, or heterocyclic radicals, such as furyl or thienyl. Furthermore, they can be substituted by radicals such as hydroxyl, lower alkoxy, amino, substituted amino, halogen, trifiuoromethyl, carboxyl or esterified carboxyl. They may further be condensed with aromatic or heterocyclic rings.

Such rhodacyanines are produced by quaternising in a manner known per se, the neutrocyanines of the general I R; O I

and reacting the resulting salt with such heterocyclic quaternary salts which have a A 1'-unsaturated cyclomethylene group in the 2-position:

the various symbols having the meaning indicated above. The position of the sensitization maximum can be displaced almost as desired by varying the heterocyclic groups and so it is possible to achieve excellent adaption to the absorption of the dyestuff images to be reproduced from a colored original, for example, a colored negative film. The dyestuffs are added to the silver halide emulsion in known manner, e.g., as methanolic solutions. The quantity used is from 15 to 150 mg. per gram of silver present as silver halide. The dyestuffs can also be used mixed with one another or with other sensitizers or nonsensitizing dyestuffs. They are particularly stable with respect to other emulsion additives, such as wetting agents, stabilizers, preservatives, plasticizers or hardeners, and in fact, their sensitizing intensity can sometimes even be increased by-. sucl:i additives as white toners of the type of diaminostilbene disulphonic acid.

According to one'preferred embodiment of the invention, the rhodacyanines are used. in emulsions containing color couplers. The color couplers can be incorporated into the emulsion in a soluble diffusion-resistant form. According to another method the color coupler is first dissolved in an inert high-boiling organic liquid, such as a phosphoric or aliphatic polycarb-oxylic acid ester, and this solution is then dispersed in a finely divided state throughout the emulsion.

The following compounds of the present invention are examples of rhodacyanine dyes which exhibit excellent utility:

Sensitization maximum u) omso. 676

II II (XIX) Sensitization maximum u) minutes at 120 C. After cooling, the .dyestuff is precipitated with 10 ml. .of 25% potassium bromide solution 3 grams of 1,3-dimethyl benzirnidazole-2,5'-(3ethyl rhodanine) and ml. of dimethyl sulphate are heated in an oil bath for minutes at 100 C. After cooling to 100 C., 4 g. of 2-cyclopentenyl benzthiazole are added, and heated while stirring for 10 minutes at 80 C. After cooling to C., the melt is triturated with 20 ml. of pyridine. 5 ml. of triethylamine are slowly added and the mixture is heated for another 10 minutes at 80 C. After cooling, the reaction solution is treated with ether and the ether is decanted. The dyestuff formed is dissolved in methanol and precipitated by adding potassium bromide solution.

Yield: 1 gram; M.P. 268-270 C.

1.9 grams of 1,3-dirnethyl-5,6-dichl0robenzimidazole- 2,5'-(3-ethyl-rhodanine) are mixed with 1 gram of 2- cyclopentenyl benzthiazole and 3 grams of dimethyl sulphate and heated in an oil bath for 5 minutes at 100 C. while stirring, the internal temperature rising to 120 C. After cooling, the melt is triturated with 20 ml. of pyridine and 2.5 ml. of triethylamine and heated for another 10 minutes at 90 C. After cooling, the reaction mass is triturated with ether and glacial acetic acid and, after decanting, the residue is formed into a paste with 5 ml. of methanol; the dyestutf which crystallizes out is suctionfiltered and washed with n-propanol. Yield: 1.5 grams; M.P. 255260 C. with decomposition. The dyestuff can be recrystallized from methanol.

1.7 grams of 3-methyl-4,S-benzobenzoxazole-2,5'-(3- ethyl-rhodanine) and 1.1 grams of 2-cyclohexenyl benzthiazole are heated with 4 ml. of dimethyl sulphate for 3 minutes at 120 C. While cooling, 10 ml. of pyridine are slowly added and the mixture is heated for another 10 and the crystals are suction-filtered and washed with propanol and ether. The crude dyestuff is crystallized from 300 ml. of methanol and ml. of chloroform.

Yield: 1.3 grams; M.P. 26l262 .C.

1.5 grams of .1-ethyl2-methyl mercaptopyrirnidine-6, 5-(3'-ethyl-rhodanine and 1.1 grams of 2-cyclopentenyl benzoxazole are heated with 4 ml. of dimethyl sulphate for 2 minutes at C. After cooling, 10ml. of pyridine are added, the temperature being kept below 120 C. Finally, the mixture is heated for 5 minutes at 120 C. After cooling, the dyestulf, which has crystallized out is suction filtered and washed withtisopropanol.

Yield: 1.7 grams; M.P. 278-291 'C.

1.5 grams of. 3-rnethyl-S-methylmercapto-l,3,4-thiodiazoline-2,5-(3-ethyloXazolid0ne-4-thione-2) and 3 grams of cyclopentenyl henzthiazole are heated with 3 ml. of diethyl sulphate for 5 minutes at 110 C. After cooling, 10 ml. of pyridineare slowly added, the temperature being :kept below 110 C., and then the temperature is maintained for another 5 minutes at this leveLAfter cooling,..the melt is triturated with ether, the dyestufl? is suc- .tion-filtered ,and washed with water and n propanol. The 65' yield is 0.5 ,gram. After dissolving in 100 ml. of methanol, 25 ml. or 25 potassium iodide solution are added. The dyestulf crystallizing out is suction filtered and washed with propanol and ether.

Yield: 0.3 gram; M.P. 252-254 C.

2.8 grams of 1 methylpyrrolidone 2,5 (isopropylidene-3'-ethyl-.rhodanine) and 5 ml. of dimethyl sulphate are heated at 110 C. The temperature then rises to C. After 5 minutes, the mixture is cooled to 100 C.,

2 grams of 2-cyclopentenyl benzthiazole are added and the whole is heated for another 10 minutes at 105 C. After cooling, 20 m1. of pyridine and 3 ml. of triethylamine are added and the mixture is heated for 10 minutes at 90 C. After cooling, the dyestulf, which crystallizes out, is suction-filtered and washed with n-propanol and ether.

Yield: 2.3 grams; M.P. 235 C.

It is recrystallized from a mixture of 300 ml. of alco hol and 50 ml. of methanol.

Yield: 0.8 gram; M.P. 258259 C.

Dyestufl VII 1.5 grams of 3-ethyl thiazolidine-Z-ethylidene-'-(3- ethyloxazolidone-4-thione-2) and 3 ml. of dimethyl sulphate are heated for minutes at 80 C. After adding 1.1 grams of cyclopentenyl benzthiazole, heating is continued for another 5 minutes at 120 C. After adding 20 ml. of acetic acid anhydride and 3 ml. of triethylamine, reaction is allowed to take place for 10 hours at room temperature. The dyestuif crystallizes out. It is suctionfiltered and washed with propanol. After recrystallization from 30 ml. of methanol, there are obtained 0.2 gram of dyestuff with an M.P. of 247 C.

Dyestufi VIII 1.9 grams of 3-ethyl benzthiazoline-2,5'-(3-ethyl selenorhodanine) and 1.1 grams of 2-cyclohexenyl benzthiazole are heated with 4 ml. of dimethyl sulphate for 3 minutes at 120 C. After cooling, 10 ml. of pyridine and 2 ml. of triethylamine are added and the mixture is heated for another 10 minutes at 120 C. The cooled melt is triturated with 30 ml. of ether. The ether is decanted and the residue, after tn'turation with 3 ml. of isopropanol, is crystallized. The crude yield is 1.4 grams; M.P. 259 C. After recrystallization from 250 ml. of methanol, there are obtained 0.85 gram; M.P. 266267 C.

3.2 grams of 3-ethyl benzthiazoline-2,5'-(3'-ethyl rhodanine) are heated with 5 ml. of dimethyl sulphate for 10 minutes at 140 C. In additional, 2 grams of 2-cyclopentenyl benzthiazole are heated with 1.3 grams of dimethyl sulphate at 110 C., the temperature rising to 125 C. The two quaternary salts are dissolved together in 20 ml. of pyridine and, after adding 1 ml. of triethylamine, stirred for 1 hour. The dyestuff which crystallizes out is suction filtered and washed with water until the filtrate is light-yellow. After brief flushing with n-propanol, the dyestuff is dried.

Yield 1 gram; M.P. 281283 C.

After recrystallization from a mixture of 200 ml. of methanol and 100 ml. of chloroform, 0.95 gram are obtained; M.P. 291293 C.

1.4 grams of 1,3-dimethyl-5-trifluoromethyl-2,5e(3'- ethyl rhodanine) and 4 ml. of dimethyl sulphate are heated for 10 minutes at 160 C. After cooling to 120 C., 2 grams of 2-cyclohexenyl benzthiazole are added and the mixture is heated for another 2 minutes at 120 C. After cooling, 10 ml. of pyridine and 1 ml. of trimethylamine are added and the mixture is heated for minutes at 120 C. After cooling, the mixture is triturated with ether, the ether is decanted off and the residue is dissolved in 50 ml. of water. 5 ml. of 50% sodium perchlorate solution are addedand the precipitated dyestulf is suction filtered. It is dissolved in 30 ml. of methanol and the suction is left to crystallize. The crude yield is 0.9 g. After recrystal- .lization from a mixture of 50 ml. of chloroform and 100 ml. of methanol, there are obtained 0.4 gram; M.P. 246- 251 C.

1.5 grams of 3-methyl benzthiazoline-2,5'-(1'-methyl- 3'-phenyl thiohydantoin) and 2.5 ml. of dimethyl sulphate are heated for 5 minutes at 140 C. and then, after cooling to C., 2 grams of 2-cyclopentenyl benzthiazole are added and the mixture is heated for another 5 minutes on the steam both. After cooling, 10 m1. of pyridine and 3 ml. of triethylamine are added and heating is continued for 10 minutes at 80 C. After cooling, the mixture is triturated with ether, the ether is decanted and the dyestuif precipitated with potassium bromide solution. The dyestuif is suction filtered, dissolved in methanol and, after adding 10 ml. of potassium bromide solution and 20 ml. of water, left for crystallization. After being suction filtered, the substance is washed with water, propanol and ether.

Yield: 0.2 gram; M.P. 201202 C.

1.4 grams of 3ethyl benzthiazoline-2,5'-(3-ethyl rhodanine), 1.4 grams of Z-cycIopentenyI-S-phenyl benzoxmole and 5 ml. of diethyl sulphate are heated for 10 minutes at 130 C. in an oil bath. After adding 10 ml. of npropanol and 3 ml. of triethylamine, the mixture is heated for another 10 minutes on a steam bath. After cooling, the dyestuff is precipitated with ether and the ether is decanted. The residue is triturated with 10 ml. of methanol and the dyestutf is suction filtered. The dyestulf is recrystallized from 350 ml. of methanol.

Yield: 0.2 gram; M.P. 20l-202 C.

2.9 grams of 3-hydroxyethyl-benzoxazoline-Z-S(3'- ethylrhodanine), 2.6 ml. of dimethylsulfate are heated together for 20 minutes at 150 C., 2.0 grams of 2-cyclopentenylbenzselenazole and 1.3 ml. of dimethylsulfate are heated together for 20 minutes at 150 C. The two melts are mixed and dissolved in 5 ml. of pyridine. After adding 2 ml. of triethylamine, the mixture is heated for 15 minutes at 80 C., the crystals which separate on cooling are sucked off and are washed with n-propanol and water. They are recrystallized from methanol-chloroform.

Yield: 0.5 gram; M.P. 295 C.

A mixture of 1.4 grams of l-butyl-pyrrolidine-2-5(3'- ethylrhodanine), 1.3 grams of 2-cyclohexenyl-benzthiazole and 2.5 ml. of dimethylsulfate are heated for 10 minutes at 120 C. After cooling to 80 C. there are added 10 ml. of pyridine, thereafter the mixture is heated for 10 minutes at C. The dyestuff which has formed is precipitated with diethylether. It is then dissolved in npropanol and precipitated by adding an aqueous solution of sodiumperchlorate. The dyestufl is sucked off and washed with ethylacetate.

Yield: 0.4 gram; M.P. 225 C.

A mixture of 1.6 grams of l-(w-carboxyethyD-py-rrolidine-2-5'(3'-ethylrhodanine) 1.3 grams of 2-cyclopentenyl-benzthiazole and 4 ml. of dimethylsulfate are heated on the steam bath to 100 C., whereby the reaction temperature rises to 140 C. After cooling the reaction mixture has added thereto 10 ml. of pyridine, whereby the temperature should not surpass 100 C. The reaction mixture is kept at this temperature for 5 minutes and thereafter the dyestutf is precipitated by means of ether.

Yield: 1.2 grams; M.P. 244 C.

A mixture of 1.9 grams of 3-methyl-5-methoxy-benzselenazoline-Z-S'(3'-ethylrhodanine), 1.3 grams of 2-cyclohexenyl-S-methyl-benzoxazole and 1.5 m1. of dimethylsulfate are heated to C. for 5 minutes. The reaction mixture is cooled to 80 C. and has added thereto 30 ml. of propanol and 3 ml. of triethylamine after 5 minutes.

There is added once more 2 ml. of triethylamine to the reaction mixture, whereafter the latter is kept 'for 5 minutes at 180 C. The dyestuif is precipitated with ether and recrystallized from methanol.

Yield: 1.3 grams; M:P. 239253 C.

A mixture of 1.3 grams of 3-methyl-5-methylmercaptothiodiazole -(1,3,4)-2,5-(3'-ethylrhodanine), 1.1 grams of 2-cyclopentenyl-S-methyl=benzthiazole and 5 ml. of die ethy'lsulfateare heated for 15 minutes to 130 C. After cooling to 80 C. there are added 10 ml. of pyridine to the reaction mixture, whereby the temperature rises to 130 C. The dyestuif which crystallizes during cooling is sucked E and washed with acetone. It is recrystallized from methanol and boiled out with ethyl acetate.

Yield: 2.1 grams; MJP. 29l293 C.

A mixture of 1.7 grams of 1-methyl-aza-cycloheptylidene 2,5'-(3'-allylrhodanine), 1.4 grams of 2-cyclopen- :tenylbenzthiazole and 3 ml. of dimethylsulfate are heated for 5 minutes at 120C. After cooling to room temperature the reaction mixture has added thereto ml. of

pyridine, whereby the reaction temperature should 'not surpass 120 C. After adding 1 ml. of triethylarnine, the reaction mixture is heated for 5 minutes on the steam bath. Thereafter it is cooled to room temperature. Then the dyestuff is precipitated with ether. Is is dissolved in 5 ml. ethanol :and precipitated .by means of .an aqueous solution of potassium iodide. Theidyestuif :is recrystallized from methanol.

Yield: 1 gram; MP. .234 1C.

Aa mixture of 1.5 grams of 1-methyl-3 ethyl1tetrazoline-2-.dimethine-5'-r(3 '--ethylrhodanine) 1. 1. grams .of 2- cyclohexenylbenzoxazole and .5 ml. of dimethylsulfate are heated on a steam bath for 5 minutes, whereby the temperature of the reaction :mixturerises to 105 :C. After cooling to room temperature the reaction mixture has added thereto 5 ml. of cacetic acid anhydride and 3 ml. of triethylamine. After heating to 75 C. themixtnre has added .thereto further-.2 ml. of triethylamine. .It is .then kept for further minutes at this temperature. The -dyestuff which has .iormed precipitates during .cooling. ,It is sucked oil, washed with water and .n-propanol and recrystallized from ethanol.

Yield: 1.2 grams; 1MP. 236 C.

A mixture of 1.7 gramsof .1,3,3-trimethylindolenine-2- dimethine-5'-(3'cthylrhodanine), 1.1 grams of 2-cyclohexenylbenzoxazole and 2 ml. of dimethylsulfate are heated for 5 minutes at .120" C. After cooling the reaction mixture .has added thereto 10 ml. of pyridine,

whereby the temperature should .not surpass 100 C.

The mixture is kept for .further 5 minutes at 100 C.

and is then cooled to room temperature. The dyestutr" 12 which crystallizes is suckedoff and washed with propanol and ethyL-acetate.

Yield: 1.6 grams M.P. 262-263 C. After .recrystallization from ml. of ethanol the yield .is 1.2 grams; M.P. 264 C.

Photographic example The sensitization of .a.silver halide emulsion is eifected in the known manner, for example, by dissolving 13 mg. of the Dyestufi I in 30.00 times the quantity of methanol and stirring the resulting solution into 1 liter of a silver chlorobromide gelatin-.emulsion at40 C. After adding the usual additives, such .as wetting agents, hardeners, stabilisers, 10 g. of 'a color coupler "for cyan, e.g., sodium-1- hydroxy-Z-naphthoic acid stearyl-amide-4-sulphonate, is

added as'a 5% solutionin'water; After adding water, the

required viscosity is adjusted and this mixture is cast onto a barytocoated paper and dried. The light-sensitive layer is exposed to light and developed in .a color .forming developer in known manner. There is obtained a spectral sensitization, the curve of which is substantially more symmetrical than that which is obtained with the conventional rhodacyanine C4115 A] 2H5 I claim:

1. A light-sensitive photographic material comprising a supported light-sensitive silver halide emulsion layer .which contains in an effective amount a sensitizing dye ofthe following. formula:

wherein R representsa radical .of the group consisting of hydrogen, .alkyil, unsaturated alky'l, alkyl substituted by :a radical of the groupwconsisting .of carboxyl, sulfo, sulfonamide, hydroxy, .and .phenyly'R v represents a member of the. group consisting of :lower alkyl, :lower alkyl substituted .by phenyl, and phenyl; .Y represents the ring members :necessary to complete .a zheterocyclic .ringof the group .consisting of .oxazole, benzoxazole, thiazole, benzthiazole, .thiodiazole, pyrimidine, pyrroline, .benzimidazole, tetrazole, azocycloheptamethylene, .selenazole, benzselenazole, naphthoxazole, oxadiazole, pyridine, pyri- .diazine, .quinol-ine, triazine, thiazine, triazole, itriazoline,

pyrazoline, and indolinepZ represents. a Lbivalent radical of the group consisting of -S, -O-, -Seand =NR R is a substituent of the group consisting of hydrogen and lower alkyl; X- is an anion; n is an integer from Oto 2 and m is an integer from .1 to .3.

2. A *light sensitivephotographic material as defined in :claim ,1, wherein "the .light-sensitive silver halide em lsion layer-yin addition contains a color coupler capable of reacting :with the oxidation product of a primary aromaticamine developerito form a dye.

3. A light-sensitive photographic material as defined in claim '2, wherein the sensitizing dye has the following formula:

l CH3 I 13 14 4. A light-sensitive photographic material as defined in 7. A light-sensitive photographic material as defined claim 2, wherein the sensitizing dye has the following in claim 2, wherein the sensitizing dye has the following formula: formula 10 a 02m 02m 8. A light-sensitive photographic material as defined in claim 2, wherein the sensitizing dye has the following formula:

5. A light-sensitive photographic material as defined in S claim 2, wherein the sensitizing dye has the following s formula: G=C/ U 0- C \1|\I/O O\ @0 ozmsor 2O C2Ha L L S s C2115 C1115 o [/l 9. A light-sensitive photographic material as defined 0H3 in claim 2, wherein the sensitizing dye has the following 25 formula:

I CH2 CH3 S s II \C i LC/ o=0 30 cHisor OH 6. A light-sensitive photographic material as defined a $2115 $2116 in claim 2, wherein the sensitizing dye has the following E formula: 00011 35 CH3 References Cited l; UNITED STATES PATENTS c1 S s 2 856 404 10/1958 Brooker et a1 96-102 7 2 C=O CHQSOF 2,882,159 4/1959 Brooker et al. 96--102 /o= 0 1 J. TRAVIS BROWN, Primary Examiner. CH3 l I NORMAN G. TORCHIN, Examiner. 

1. A LIGHT-SENSITIVE PHOTOGRAPHIC MATERIAL COMPRISING A SUPPORTED LIGHT-SENSITIVE SILVER HALIDE EMULSION LAYER WHICH CONTAINS IN AN EFFECTIVE AMOUNT A SENSITIZING DYE OF THE FOLLOWING FORMULA: 